I think I have found out why:
Mar 7 13:52:45 srv sendmail[30506]: i27Jqjx30506: ruleset=check_mail, arg1=
ct=553 5.1.8
Mar 7 13:52:45 srv sendmail[30506]: i27Jqjx30506: from=
=MTA, relay=[207.218.223.172]
can you please fix it if this is what is causing my problems? Noone else has such situation?